Fluorosulfonylimides such as N-(fluorosulfonyl)-N-(fluoroalkylsulfonyl)imide and di(fluorosulfonyl)imide, and derivatives thereof are useful as intermediates for compounds having a N(SO2F) group or an N(SO2F)2 group, and are also useful compounds in various applications, for example, electrolytes, additives for electrolytic solutions of fuel cells, selective electrophilic fluorinating agents, photo acid generators, thermal acid generators, and near infrared light-absorbing dyes.
Di(fluorosulfonyl)imides described above have conventionally been prepared by a halogen exchange reaction of di(chlorosulfonyl)imide using a fluorinating agent. For example, arsenic trifluoride (AsF3) is used as a fluorinating agent in Non-patent Document 1 (John K. Ruff and Max Lustig, Inorg Synth. 11, 138-140 (1968)) and antimony trifluoride (SbF3) is used as a fluorinating agent in Non-patent Document 2 (Jean'ne M. Shreeve et al., Inorg. Chem. 1998, 37(24), 6295-6303). Patent Document 1 (Japanese Published Patent Publication No. 2004-522681) describes a method in which di(chlorosulfonyl)imide is fluorinated using an ionic fluoride of monovalent cations, such as KF or CsF as a fluorinating agent. Also, Patent Document 2 (Japanese Published Patent Publication No. H08-511274) discloses a method in which di(fluorosulfonyl)imide is prepared by distilling fluorosulfonic acid (HFSO3) in the presence of urea.